SUPERPLASTIC FORMING

Superplastic forming module is used to analyze the formability of sheet metal under superplastic temperature and subjected to applied pressure. The setup of forming process is similar to the forming process using common sheet metal, with an exception for the Process setup described in the following section.

Figure 8.2.116  Superplastic forming

 

8.2.9.1  PROCESS

Process page enables the setup of basic process parameter for superplastic forming such as pressure curve, percent to terminate, tool contact, desired strain rate, termination time, etc. The user can modify process parameters according to practical situation. Process page for superplastic forming is illustrated in Figure 8.2.117.

 

The user can select one or two phase analysis. If one phase analysis is selected, the sheet is directly formed into the final part shape by applied pressure. If two phase analysis are selected, preforming is performed in the first phase to partially or fully make the sheet to confront to preformed die. In second phase, reverse pressure is applied to confront the sheet to die geometry to obtain the final part shape. Pressure and reverse pressure are usually used for superplastic forming process to obtain even part thickness.

 

PHASE I

Define parameters such as pressure curve, percent to terminate and contact tool.

 

      PRESSURE CURVE

      Click on <none> button to define pressure curve using EDIT LOAD CURVE dialog box described in previous section.

 

      CONTACT TOOL

      Select tools contacting with sheet.

 

      PERCENT TO TERMINATE

      Enter the contact node percent between sheet and selected contact tool. The user can use contact node percent to control the termination time of this phase. If the sheet contacts with 80% nodes of the contact tool, this forming phase is terminated.

 

SPF

Figure 8.2.117  Process page

 

      PERCENT TO AUTOJUMP

      Key in the contact node percent in this field if autojump option is selected in the Advanced dialog box. The current phase is automatically terminated if the contact nodes reach the input percent.

 

PHASE II

 

If part is formed in two phases, the definition of parameters for Phase II is added to the interface. The definition of parameter for Phase II is similar to Phase I. Refer to the above description.

 

COMMON

      DESIRED STRAIN RATE (ERATE)

      Set desired strain rate. Strain rate is the derivative of equivalent plastic strain with respect to time.

 

      ADVANCED

      Set advanced forming parameters. Refer to LS-DYNA User’s Manual for description about advanced setting.

advanced

Figure 8.2.118  Advance setting for superplastic forming